1
Adjust rack to top position (middle and top positions for 4 servings) and preheat oven to 425 degrees. Wash and dry all produce.
Dice potatoes into ½-inch pieces. Halve and core apple; grate one half on the largest holes of a box grater (grate whole apple for 4). Zest and quarter lemon. Trim and thinly slice scallions, separating whites from greens; mince whites.